Hail and Damaging Wind in Oklahoma, May 11, 2001

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
210 PM CDT FRI MAY 11 2001

TSRA CONTINUE TO DEVELOP ALONG COLD FRONT NEAR THE KANSAS/OKLAHOMA BORDER
AND ALONG OUTFLOW BOUNDARY ACROSS NORTHEAST OKLAHOMA. MEANWHILE
CONTINUE TO WATCH SLOW PROGRESS OF MCV ACROSS SOUTHWEST OKLAHOMA WHICH
HAS RESULTED IN MOSTLY SCATTERED ELEVATED SHRA. BEST AREAL COVERAGE OF
PRECIP HAS BEEN ACROSS NORTH CENTRAL AND NORTHEAST OKLAHOMA WHERE CAP
IS WEAKEST. MID/UPPER LEVEL DEFORMATION SHOULD SUSTAIN CONVERGENCE
ALONG THESE BOUNDARIES OVERNIGHT WITH NORTHWEST MID LEVEL FLOW BRINGING
CONVECTION SOUTHWARD INTO MOST OF THE EASTERN HALF OF THE AREA. PLAN ON
HIGHEST POPS MAINLY ALONG AND EAST OF INTERSTATE 35 WITH CHANCE POPS FOR
AREAS WEST OF INTERSTATE 35. WILL MONITOR LATEST RADAR TRENDS BEFORE
ISSUANCE FOR FINAL DECISION. NOT SURE HOW FAR SOUTH COLD FRONT WILL BE
BY 12 SATURDAY ALTHOUGH OUTFLOW BOUNDARY FROM OVERNIGHT CONVECTION MAY
EFFECTIVELY ACT AS THE PRIMARY CONVERGENCE ZONE WELL SOUTH OF IT. IN
ADDITION TO THE POSSIBILITY OF LINGERING MORNING CONVECTION...CONCERNED
THAT POOLING OF BOUNDARY LAYER MOISTURE MAY TAKE PLACE NORTH OF
SYNOPTIC BOUNDARY SATURDAY ALLOWING THE ATMOSPHERE TO DESTABILIZE QUITE
EASILY WITH ADDITIONAL DIABATIC HEATING WITH ONLY WEAK LIFT LIKELY
REQUIRED FOR NEW DEVELOPMENT. SO WILL MAINTAIN SMALL POPS FOR THE
SOUTHERN TIER FOR ALL OF SATURDAY. BY SATURDAY NIGHT/SUNDAY IT APPEARS
UPPER RIDGE AND SUBSIDENCE WILL GRADUALLY STRENGTHEN WITH LITTLE TO NO
CHANCE OF PRECIP CONTINUING THROUGH MONDAY.

IN THE EXTENDED...SIGNIFICANT DIFFERENCES IN THE LONGWAVE PATTERN ARE
DISPLAYED BY THE GLOBAL MODELS BY DAYS 3 AND 4 WHICH ARE LIKELY DUE TO
POORLY RESOLVED SHORTWAVES MOVING QUICKLY INTO THE WEST COAST ANY OF
WHICH COULD RESULT IN PRECIP CHANCES. WITH SO MUCH UNCERTAINTY THIS FAR
OUT AND THE POTENTIAL FOR QUICK MOISTURE RETURN AND CLIMATOLOGICALLY
GREATER INSTABILITY PLAN TO ERROR ON THE SIDE OF CAUTION AND CONTINUE
WITH CHANCE POPS FOR TUESDAY THROUGH FRIDAY.

GAG 55/80/58/86/61 30000
PNC 55/79/56/82/64 40000
HBR 60/80/56/84/64 32000
OKC 60/79/56/82/65 80000
SPS 65/81/60/84/65 33000
DUR 64/80/56/81/60 43000

.OUN...
OK...NONE.
TX...NONE.
JAMES

OKZ004>048-050>052-TXZ083>090-112000-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NORMAN OK
100 PM CDT FRI MAY 11 2001

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THROUGH TONIGHT
ACROSS MUCH OF OKLAHOMA AND WESTERN NORTH TEXAS...SOUTHEAST OF A LINE
FROM ERICK TO ALVA. THE RISK OF SEVERE WEATHER IS MARGINAL... WITH
ONLY ISOLATED REPORTS OF MARGINALLY SEVERE HAIL EXPECTED. LOCALLY
HEAVY RAIN AND STRONG WINDS ALSO ARE POSSIBLE.

A COLD FRONT WAS MOVING SOUTHEAST ACROSS NORTHWEST OKLAHOMA AT
MIDDAY... AND WILL MOVE INTO SOUTHWEST AND CENTRAL OKLAHOMA BY THIS
EVENING. AN OUTFLOW BOUNDARY... FROM STORMS OVER SOUTHEAST KANSAS AND
SOUTHERN MISSOURI... WAS ACROSS NORTH CENTRAL AND NORTHEAST
OKLAHOMA... AND INTERSECTED THE FRONT OVER FAR NORTH CENTRAL
OKLAHOMA. THUNDERSTORMS ARE EXPECTED TO CONTINUE DEVELOPING NEAR THIS
INTERSECTION THIS AFTERNOON OVER NORTH CENTRAL OKLAHOMA...WITH A FEW
POSSIBLY BECOMING SEVERE.

FARTHER SOUTH... A MID LEVEL DISTURBANCE WAS CENTERED OVER SOUTHWEST
OKLAHOMA... MOVING SOUTHEAST. SCATTERED SHOWERS AND THUNDERSTORMS
WILL BE POSSIBLE THIS AFTERNOON TO THE EAST THROUGH SOUTH OF THIS
DISTURBANCE. MOST OF THE SHOWERS WILL FORM WITHIN A LAYER OF UNSTABLE
AIR AT MID LEVELS. CLOUD COVER WILL ACT TO INHIBIT AFTERNOON HEATING
AND DESTABILIZATION OF THE LOW LEVELS IN THESE AREAS. ALTHOUGH BREAKS
ARE EXPECTED IN THE CLOUD COVER... SURFACE BASED INSTABILITY IS
NOT EXPECTED TO BE ENOUGH TO ALLOW ANY THUNDERSTORMS TO BECOME
SURFACE BASED. ALSO...WINDS ALOFT ARE RELATIVELY WEAK AT ALL
LEVELS...SO THE VERTICAL WIND PROFILE IS NOT FAVORABLE FOR ORGANIZED
SEVERE THUNDERSTORMS. THE SITUATION FAVORS SHORT-LIVED... SLOW 3MOVING
PULSE TYPE STORMS. ALTHOUGH ISOLATED STORMS MAY PRODUCE HEAVY RAIN
AND SOME DIME TO QUARTER SIZE HAIL... AND POSSIBLY SOME STRONG
OUTFLOW WINDS... THE OVERALL CHANCE OF SEVERE WEATHER IS LOW.

&&

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